The star that led the three wise men could be the same star wished upon this Christmas-time by three young women.     In the opening story, "Christmas Child," 15-year-old Melanie feels cheated when her baby sister, born during the holidays, lives only a few hours. But the baby's brief life shows Melanie the lasting value of love.     Brenda struggles between noble intentions and earthier desires when she becomes a dying boy's final chance for happiness in "Last Dance."     The closing story, "Kathy's Life," presents a 16-year-old who appears to have it all. Kathy is beautiful, intelligent, and has the perfect job as a live-in caretaker for a couple's baby boy. But not everything is as perfect as it seems.
